Regenerative blowers are useful for moving large volumes of a fluid, such as air or other gas, at lower pressures or vacuums. Unlike positive displacement compressors and vacuum pumps, regenerative blowers, which are also referred to as side channel blowers or ring compressors, regenerate fluid molecules via non-positive displacement method to create vacuum or pressure. Regenerative blowers are used in a broad range of applications, such as pneumatic conveying, sewage aeration, vacuum lifting, vacuum packaging, packaging equipment, printing presses, aquaculture/pond aeration, spas, dryers, dust/smoke removal, industrial vacuum systems, soil vapor extraction, and chip removal for engraving equipment. Anywhere high fluid flow and low vacuum/pressure are required, regenerative blowers are an ideal solution as a properly installed regenerative blower will provide years of service-free operation.
A typical regenerative blower includes an impeller mounted directly to a motor shaft, which spins at the motor's nominal speed, such as 2900-3500 revolutions per minute. The impeller consists of numerous blades formed on its circumference. The number, size, and angle of these blades contribute to the pneumatic performance characteristics of the blower. The impeller spins within a housing assembly having a channel between an inlet and an outlet. As the impeller rotates, the fluid, such as air or other gas, is forced through the channel from the inlet to the outlet. The fluid is pressurized as it passes through the channel from the inlet to the outlet, in which the fluid discharged through the outlet is at a higher relative pressure than that of the fluid entering the channel through the inlet. The intake region of the channel near the inlet is the low pressure region of the blower, and the discharge region of the channel near the outlet is the high pressure region of the blower. As the fluid is forced through the channel from the inlet to the outlet, the fluid is captured between each blade on the impeller and is pushed both outward and forward into the channel. The fluid then returns to the base of the blade. This process is repeated over and over as the impeller spins, and it is this regeneration that gives the blower its pressure/vacuum capabilities. And so a regenerative blower operates like a staged reciprocal compressor and while each blade to blade regeneration stage results in only slight pressure increases, the sum total of the slight pressure increases through the channel from the inlet to the outlet can yield comparatively higher continuous operating pressures.
Regenerative blowers require little if any maintenance and monitoring because the impeller is wear-free because it does not come into contact with the housing assembly channel. Self-lubricated bearings are the only wearing parts. Regenerative blowers are oil-less and have no complicated intake and exhaust valving. Furthermore, most blower makes can be mounted in any plane and with dynamically balanced impellers that generate little vibration. Because there are few moving parts, regenerative blowers rarely fail unless they are installed or operated improperly.
However, regenerative blowers have close internal tolerances between the impeller and the housing assembly, which requires that the blower be kept free of debris that could become wedged between the impeller and housing assembly that could cause the blower to fail. A filter, such as a 10 micron filter, is often used to prevent the intake of unwanted debris, most manufacturers of regenerative blowers offer filters and relief valves as accessories for their blowers. Nevertheless, manufacturing the impeller and the housing assembly at close tolerances requires highly specialized equipment and is tedious and expensive. Furthermore, regenerative blowers are now being manufactured to allow the blade-to-blade regeneration stages to operate at increasingly higher pressures, such as from 1.2 to 1.4 psig, in order to produce increasingly higher discharge pressures. This is increasingly common in single-stage regenerative blowers. At these increased blade-to-blade regeneration stage pressures, however, leakage occurs between the impeller and the housing assembly from the high pressure to the low pressure region of the housing assembly, which reduces blower efficiency. Given these and other deficiencies in the art of regenerative blowers, continuing improvement in the art is evident.